Metering device



W. ASLAN METERING DEVICE June 13, 1967 Original Filed Dec. 3, 1962 OW VINVENTOR Wilfred Asian BY I &M% I%J A, 4rM- AT RNEYS United StatesPatent 3,324,892 METERING DEVICE Wilfred Aslan, Mahwah, N.J., assignorto Alkon Products Corporation, Hawthorne, N.J., a corporation of NewYork Original application Dec. 3, 1962, Ser. No. 241,666, now Patent No.3,247,767, dated Apr. 26, 1966. Divided and this application Oct. 15,1965, Ser. No. 496,564

1 Claim. (Cl. 13845) This application is a division of my copendingapplication, Ser. No. 241,666, filed Dec. 3, 1962, therefor; entitledFluid Cylinder, which issued as Patent No. 3,247,- 767 on Apr. 26, 1966.The present invention relates generally to improvements in meteringvalves adapted to be used in fluid cylinders of the pneumatic orhydraulic type and more particularly to a metering valve having anadjusting screw for regulating the rate of flow of fluid through ametering passage, and an associated housing construction which iscompressively loaded to effect a sealing of the metering device Withinthe cylinder housing which sealing is unaffected by subsequentadjustment of the screw.

In providing a pneumatic or hydraulic type of fluid cylinder, forexample, with a screw type of adjustable metering device having ametering screw threadably ositioned in the housing of the meteringdevice and with the entire device, in turn, threaded into the housing ofthe cylinder, difficulties have been encountered in assuring that themetering device remains sealed in the cylinder housing against leakageof fluid. These difficulties have arisen due to the requirement that themetering screw he constructed for movement within the housing structureof the metering device to control the cross-sectional dimension of themetering passage. Such movement of the metering screw has the tendencyof upsetting the seal between the relatively movable parts of themetering device; and the fluid within the hydraulic cylinder being underpressure tends to escape around these opposed surfaces if the sealbetween them is so disturbed.

In accordance with the teachings of the present invention, a screw typeof metering device is provided with a seal that is automaticallycompressively loaded upon the original insertion of the metering deviceinto the housing of the cylinder. Once the metering device has beenconnected to the cylinder housing in sealed relationship therewith, themetering screw may be adjusted axially of the device without disruptingthe relative position of the remaining parts of the device and thereforewithout upsetting the seal.

In accordance with the teachings of the present invention, a gland nutis provided for connecting an adjustable metering screw to the end capof a fluid cylinder, for example. Surrounding the shaft of the screw isa packing disc, a back-up washer and a spring washer of the Bellevilletype in that order. When the gland nut is assembled to the end cap ofthe fluid cylinder, the spring washer is brought to bear against aninternal shoulder within the cylinder cap. The spring washer thereafterwill exert a compressive resilient loading upon the back-up washer andupon the packing, with the latter in sealing engagement with the threadsof the metering screw and the wall surface of the bore which receivesthe gland nut. The screw may thereafter be adjusted axially to secure aproper flow of fluid through the metering passage and at all timesduring such adjustment, the spring washer will exert a sufficientpressure upon the packing which engages the threads of the screw toassure that leakage will not occur.

A more complete understanding of the present invention and the operationthereof will be obtained from a 3,324,892 Patented June 13, 1967 readingof the following specification with reference being made to theaccompanying drawings of which:

FIG. 1 is a longitudinal cross-sectional view of a fluid cylinderconstructed to include the metering device of the present invention; and

FIG. 2 is an enlarged detail of the metering device shown in FIG. 1.

Referring now to the drawings, a fluid cylinder 10 has been illustratedhaving end caps 11, 12 which are secured at each end to an intermediatecylindrical body 13. O- ring seals 14, 15 are provided to effect fluidseals at the junctures of the caps and the cylinder body. The cap 12journals a piston rod 16, one end 16a thereof projecting from the cap 12for attachment to a device to be operated or moved by the cylinder 10.The cap 12 threadedly receives a journal bushing 17 having pressureresponsive seal members 18, 19 for engaging portions of the rod 16 toprevent leakage past the rod from the interior of the cylinder.

A piston 29 is mounted to the rod 16 adjacent the internal end thereoffor reciprocating movement within the cylinder body 13. The piston 20has pressure responsive seal members 21, 22 for effecting a seal betweenthe periphery of the piston and the interior wall surface of thecylinder body 13 upon the admission of a pressure fluid into thecylinder body 13 for driving the piston. Pressure fluid will be admittedto chambers 23 and 24 alternately through ports 26, 27 in the end caps12, 11. It will be understood that each of the ports 26, 27 will alsoserve as an exhaust orifice for evacuating a chamber 23, 24 during onehalf of a cycle.

The piston rod 16 carries adjacent opposite faces of the piston 20,cushion units designated generally by reference numerals 28, 28. The endcap 11 of the cylinder defines a bore 30 having an area of reduceddiameter 32 immediately adjacent to the chamber 24. When the piston 20is driven toward the right by the admission of a pressure fluid throughthe port 26 and into the chamber 23, fluid in chamber 24 will first bepermitted to escape through the bore 36 and therefrom through the port27. But as the piston nears the end of its stroke, the cushion element28 will begin to enter the neck or reduced area 32 of the bore 30.

As the cushion element 28 achieves a seal within the bore 32, thepressure in chamber 24 will increase and provide a gradual deceleratingeffect against the right face of the piston 20. In order to continuemovement of the piston to the end of its stroke, bypass meteringpassages 34, 36 are provided which conduct fluid from the chamber 24 tothe chamber 38 and therefrom through the exhaust orifice 27. From anexamination of the drawings, it will be apparent that the cushion unit28 will operate in the same manner as has been described in connectionwith the cushion unit 28.

In accordance with the teachings of the present invention, the degree ofcushioning provided in the cylinder is made variable 'by means of ametering screw device 40. Although only one such metering device isshown at the right hand end of the cylinder, it is to be understood thatan identical structure could be included at the left hand end of thecylinder.

In accordance with the invention, reference is made to FIG. 2 whereinthe metering device 40 is shown in detail. The device 40 includes agland 42 which carries a central metering screw 43 having afrusto-conical metering surface 43a at the upper end thereof. The gland42 further carries a disc shaped packing 44 threaded on the insidediameter as shown in FIG. 2 to mate with the threaded surface of themetering screw, a retainer washer 46 and a Belleville spring disc washer47 in succession. The metering screw device 40 is installed within thecap 11 by first threading the gland 42 into a tapped bore at the cap 11provided for that purpose. The gland 42 will be provided with spannerwrench holes or similar means for applying torque thereto and will beturned until the gland bottoms against a shoulder 48 in the cap. Thespring washer 47 will previously have abutted a second internal shoulder49 and during the final threading of the gland 42 toward and against theshoulder 48, the washer 47 will exert compressive loading upon theretainer 46 and upon the packing 44. The packing under such compressiveforce will cold-flow into the thread grooves of the screw 43 therebyeffecting a seal and further will effect a seal about its periphery withthe adjacent wall surface of the cap. Satisfactory materials for thepacking are harder grades of synthetic rubber and many plastic materialssuch as nylon and Teflon.

The advantage of the foregoing arrangement is that once the gland 42 hasbeen originally installed, its position and the relative positions ofthe members 44, 46 and 47 need not be changed materially in order toeffect adjusting movement of the metering screw 43. The latter may beadjusted axially in accordance with metering requirements to vary thefiow of fluid in the passages 34, 36 providing the cushion effectdesired, and since the washer 47 constantly exerts compressive loadingupon the packing 44 the seal between the packing and the threads of thescrew 43 will be maintained. Satisfactory sealing after repeatedadjustments have been made at varying pressures from vacuum to 10,000psi.

It will be understood that the foregoing description relates to aparticular embodiment of the invention and is merely representative.Therefore, in order to appreciate fully the spirit and scope of thepresent invention, reference should be made to the appended claim, inwhich,

I claim:

An adjustable metering device for regulating the flow of fluid through awalled passageway comprising a gland nut, a threaded metering bore inthe wall of said passageway for receiving said nut, a metering screwcarried by said nut in axial alignment therewith for insertion withinsaid passageway, said screw being threaded centrally to said nut andadjustable axially relative thereto, an internally threaded disc-likeresilient packing seal of a material having permanent cold flowproperties disposed adjacent to the inner face of said nut and inthreaded engagement with the thread of said screw, a flat retainercontinuously disposed adjacent to said packing, a spring washer disposedadjacent to said retainer with central portions thereof in contact withsaid retainer, a shoulder defined within said metering bore foreffecting compression of said washer toward said retainer, packing sealand nut upon threading of said nut into said metering bore toresiliently load said seal into permanently deformed engagement withsaid screw and hold said nut, seal, retainer and washer in substantiallyfixed position upon axial adjustments of said screw.

References Cited UNITED STATES PATENTS 1,572,922 2/1926 Govers et a1 277X 1,583,050 5/1926 Keller 13846 X 2,646,959 7/1953 Carver 277-112 X3,192,942 7/1965 Manor et al 277-106 X LAVERNE D. GEIGER, PrimaryExaminer.

T. L. MOORHEAD, Assistant Examiner.

